These sites are great for stock video footage:
Most of this is adobe, but chunks are just videos which can be used on multiple projects:
You can download this content and play with it… But it's not royalty free (don't use it in something you plan to release).
Getting “Free” (at least for non commercial, or with attribution) sound is hard work. DaVinci Resolve does have a free Foley sound library (see details under Sound FX below), and there are many places you can pay for subscriptions to audio. I always recommend that people start with the YouTube Library:
You can filter music for “Attribution Not Required” if you want to post something without putting a credit in, otherwise most of the music is pretty happy to be used without any cost and you just need to put some attribution. There is also a large collection of sound FX.
If you can't find what you want there, then try the links below.
DaVinci Resolve/Black Magic Fairlight Foley Sound FX:
Other libraries:
A tutorial on cinematic sounds EASY CINEMATIC SOUND DESIGN for FILMMAKING - Premiere Pro Tutorial worth looking at.